152 lines
5.7 KiB
Diff
152 lines
5.7 KiB
Diff
From d0bf64abd7f837c5faf16e0550d678aed630e520 Mon Sep 17 00:00:00 2001
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From: Josh Poimboeuf <jpoimboe@redhat.com>
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Date: Fri, 12 Apr 2019 15:39:29 -0500
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Subject: [PATCH 24/30] x86/speculation: Support 'mitigations=' cmdline option
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commit d68be4c4d31295ff6ae34a8ddfaa4c1a8ff42812 upstream
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Configure x86 runtime CPU speculation bug mitigations in accordance with
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the 'mitigations=' cmdline option. This affects Meltdown, Spectre v2,
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Speculative Store Bypass, and L1TF.
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The default behavior is unchanged.
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Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Tested-by: Jiri Kosina <jkosina@suse.cz> (on x86)
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Reviewed-by: Jiri Kosina <jkosina@suse.cz>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: "H . Peter Anvin" <hpa@zytor.com>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Jiri Kosina <jikos@kernel.org>
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Cc: Waiman Long <longman@redhat.com>
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Cc: Andrea Arcangeli <aarcange@redhat.com>
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Cc: Jon Masters <jcm@redhat.com>
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Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Cc: Paul Mackerras <paulus@samba.org>
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Cc: Michael Ellerman <mpe@ellerman.id.au>
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Cc: linuxppc-dev@lists.ozlabs.org
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Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
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Cc: linux-s390@vger.kernel.org
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Cc: Catalin Marinas <catalin.marinas@arm.com>
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Cc: Will Deacon <will.deacon@arm.com>
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Cc: linux-arm-kernel@lists.infradead.org
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Cc: linux-arch@vger.kernel.org
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Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cc: Tyler Hicks <tyhicks@canonical.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Randy Dunlap <rdunlap@infradead.org>
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Cc: Steven Price <steven.price@arm.com>
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Cc: Phil Auld <pauld@redhat.com>
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Link: https://lkml.kernel.org/r/6616d0ae169308516cfdf5216bedd169f8a8291b.1555085500.git.jpoimboe@redhat.com
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---
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Documentation/admin-guide/kernel-parameters.txt | 16 +++++++++++-----
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arch/x86/kernel/cpu/bugs.c | 11 +++++++++--
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arch/x86/mm/pti.c | 4 +++-
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3 files changed, 23 insertions(+), 8 deletions(-)
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diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
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index 6a1b94afb005..31c17532c219 100644
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--- a/Documentation/admin-guide/kernel-parameters.txt
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+++ b/Documentation/admin-guide/kernel-parameters.txt
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@@ -2503,15 +2503,20 @@
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http://repo.or.cz/w/linux-2.6/mini2440.git
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mitigations=
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- Control optional mitigations for CPU vulnerabilities.
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- This is a set of curated, arch-independent options, each
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- of which is an aggregation of existing arch-specific
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- options.
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+ [X86] Control optional mitigations for CPU
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+ vulnerabilities. This is a set of curated,
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+ arch-independent options, each of which is an
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+ aggregation of existing arch-specific options.
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off
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Disable all optional CPU mitigations. This
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improves system performance, but it may also
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expose users to several CPU vulnerabilities.
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+ Equivalent to: nopti [X86]
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+ nospectre_v2 [X86]
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+ spectre_v2_user=off [X86]
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+ spec_store_bypass_disable=off [X86]
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+ l1tf=off [X86]
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auto (default)
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Mitigate all CPU vulnerabilities, but leave SMT
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@@ -2519,12 +2524,13 @@
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users who don't want to be surprised by SMT
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getting disabled across kernel upgrades, or who
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have other ways of avoiding SMT-based attacks.
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- This is the default behavior.
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+ Equivalent to: (default behavior)
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auto,nosmt
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Mitigate all CPU vulnerabilities, disabling SMT
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if needed. This is for users who always want to
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be fully mitigated, even if it means losing SMT.
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+ Equivalent to: l1tf=flush,nosmt [X86]
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mminit_loglevel=
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[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
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diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
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index 8d432a3d38a3..904d55cf80a2 100644
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -494,7 +494,8 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
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char arg[20];
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int ret, i;
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- if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
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+ if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") ||
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+ cpu_mitigations_off())
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return SPECTRE_V2_CMD_NONE;
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ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
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@@ -756,7 +757,8 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void)
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char arg[20];
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int ret, i;
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- if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable")) {
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+ if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") ||
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+ cpu_mitigations_off()) {
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return SPEC_STORE_BYPASS_CMD_NONE;
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} else {
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ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable",
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@@ -1077,6 +1079,11 @@ static void __init l1tf_select_mitigation(void)
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if (!boot_cpu_has_bug(X86_BUG_L1TF))
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return;
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+ if (cpu_mitigations_off())
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+ l1tf_mitigation = L1TF_MITIGATION_OFF;
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+ else if (cpu_mitigations_auto_nosmt())
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+ l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
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+
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override_cache_bits(&boot_cpu_data);
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switch (l1tf_mitigation) {
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diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
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index c1fc1ae6b429..4df3e5c89d57 100644
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--- a/arch/x86/mm/pti.c
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+++ b/arch/x86/mm/pti.c
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@@ -35,6 +35,7 @@
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/uaccess.h>
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+#include <linux/cpu.h>
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#include <asm/cpufeature.h>
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#include <asm/hypervisor.h>
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@@ -115,7 +116,8 @@ void __init pti_check_boottime_disable(void)
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}
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}
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- if (cmdline_find_option_bool(boot_command_line, "nopti")) {
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+ if (cmdline_find_option_bool(boot_command_line, "nopti") ||
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+ cpu_mitigations_off()) {
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pti_mode = PTI_FORCE_OFF;
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pti_print_if_insecure("disabled on command line.");
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return;
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